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Aberrant overexpression of ADAR1 promotes gastric cancer progression by activating mTOR/p70S6K signaling.

ABSTRACT: ADAR1, one of adenosine deaminases acting on RNA, modulates RNA transcripts through converting adenosine (A) to inosine (I) by deamination. Emerging evidence has implicated that ADAR1 plays an important role in a few of human cancers, however, its expression and physiological significance in gastric cancer remain undefined. In the present study, we demonstrated that ADAR1 was frequently overexpressed in gastric cancer samples by quantitative real-time PCR analysis. In a gastric cancer tissue microarray, ADAR1 staining was closely correlated with tumor stage (P < 0.001) and N classification (P < 0.001). Functional analysis indicated that ADAR1 overexpression promoted cell proliferation and migration in vitro, whereas ADAR1 knockdown resulted in an opposite phenotypes. Furthermore, ADAR1 knockdown also inhibited tumorigenicity and lung metastasis potential of gastric cancer cells in nude mice models. Mechanistically, ADAR1 expression had a significant effect on phosphorylation level of mTOR, p70S kinase, and S6 ribosomal protein, implying its involvement in the regulation of mTOR signaling pathway. We conclude that ADAR1 contributes to gastric cancer development and progression via activating mTOR/p70S6K/S6 ribosomal protein signaling axis. Our findings suggest that ADAR1 may be a valuable biomarker for GC diagnosis and prognosis and may represent a new novel therapeutic opportunities.

SUBMITTER: Dou N

PROVIDER: S-EPMC5349904 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Aberrant overexpression of ADAR1 promotes gastric cancer progression by activating mTOR/p70S6K signaling.

Dou Ning N Yu Shijun S Ye Xiaojuan X Yang Dong D Li Yandong Y Gao Yong Y

Oncotarget 20161201 52

ADAR1, one of adenosine deaminases acting on RNA, modulates RNA transcripts through converting adenosine (A) to inosine (I) by deamination. Emerging evidence has implicated that ADAR1 plays an important role in a few of human cancers, however, its expression and physiological significance in gastric cancer remain undefined. In the present study, we demonstrated that ADAR1 was frequently overexpressed in gastric cancer samples by quantitative real-time PCR analysis. In a gastric cancer tissue mic ...[more]

PMID: 27863387

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Project description:BackgroundHepatocellular carcinoma (HCC) is the sixth most common cancer and the second leading cause of cancer-related deaths worldwide. Despite new technologies in diagnosis and treatment, the incidence and mortality of HCC continue rising. And its pathogenesis is still unclear. As a highly conserved protein of the Golgi apparatus, Golgi phosphoprotein 3 (GOLPH3) has been shown to be involved in tumorigenesis of HCC. This study aimed to explore the exact oncogenic mechanism of GOLPH3 and provide a novel diagnose biomarker and therapeutic strategy for patients with HCC.MethodsFirstly, the expression of GOLPH3 was detected in the HCC tissue specimens and HCC cell lines. Secondly, RNA interference was used for GOLPH3 gene inhibition. Thirdly, cell proliferation was analyzed by MTT; cell apoptosis was analyzed by Annexin-V/PI staining, Hoechst 33,342 staining and caspase 3/7 activity assay. Fourthly, xenograft tumor model was used to study the function of GOLPH3 in tumor growth in vivo. Finally, western blotting and immunohistochemistry were used to investigate the role of GOLHP3 in the mTOR signaling pathway.ResultsData showed that the mRNA and protein expression of GOLPH3 were up-regulated in HCC tumor tissue and cell lines compared with those of control (P < 0.05). Correlation analyses showed that GOLPH3 expression was positively correlated with serum alpha-fetoprotein level (AFP, P = 0.006). Knockdown GOLPH3 expression inhibited proliferation and promoted apoptosis in HCC cell lines. What's more, knockdown GOLPH3 expression led to tumor growth restriction in xenograft tumor model. The expression of phosphorylated mTOR, AKT and S6 K1 were significantly higher in HCC tumor tissue and cell lines compared with those in normal liver tissues (p < 0.05). While the phosphorylated mTOR, AKT and S6 K1 were much lower when diminished GOLPH3 expression in HCC cell lines both in vitro and in vivo.ConclusionThe current study suggests that GOLPH3 contributes to the tumorigenesis of HCC by activating mTOR signaling pathway. GOLPH3 is a promising diagnose biomarker and therapeutic target for HCC. Our study may provide a scientific basis for developing effective approaches to treat the HCC patients with GOLPH3 overexpression.

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Aberrant overexpression of ADAR1 promotes gastric cancer progression by activating mTOR/p70S6K signaling.

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Aberrant overexpression of ADAR1 promotes gastric cancer progression by activating mTOR/p70S6K signaling.

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